1. Field of the Invention
This invention relates to fluid control valves and, more specifically, to valves which are capable of automatically controlling fluid flow to a predetermined rate despite line pressure variations.
2. Description of the Prior Art
In large buildings of modern construction, heating or cooling fluids are pumped from a central boiler or refrigeration unit through an extensive network of pipes to individual heat exchangers positioned for optimum comfort of the occupants of the building. Because of the frictional forces experienced by the fluids in flowing to distant heat exchangers, significant line pressure drops occur and the rate of flow through the distant heat exchangers, being a direct function of fluid pressure, is low, with unsatisfactory heating or cooling results. These heating or cooling systems are closed fluid-flow systems. Similar undesirable effects are experienced in open fluid-flow systems, for example, in supplying hot or cold water to many outlets of varying distances from a water source.
One approach to equalizing the fluid is to install manually adjustable valves on the upstream side of those utilization devices or outlets which are near the central fluid source. By partially closing such valves, a resistance to flow is inserted in the line to the associated exchanger or outlet and the rate of fluid flow at the most distant exchangers or outlets. Unfortunately, such valves do not assure uniform fluid flow under varying source or head pressures and improper heating or cooling action or excessive fluid use occurs.
Therefore, it is an object of this invention to provide a flow-control valve which overcomes the various problems and disadvantages which have been described hereinbefore as being encountered in the use of fluid-control valves of the prior art.
It is a further object of the present invention to provide a fluid-flow control valve which will assure fluid flow at a predetermined rate despite wide ranges in source pressure variations.
It is a still further object of the present invention to provide a fluid-flow control valve which is simple in construction and effective despite small pressure differentials across it.
It is an additional object of the present invention to provide a fluid-flow control valve which is bi-laterally effective and suffers minimally from failures due to occlusion by foreign particles in the flow-control mechanism.